Field of the Invention
The present subject matter relates to improvements to existing marking materials and compositions for use in marking operations in conjunction with commercially available lasers and/or diodes and various methods of marking and decorating a variety of different substrate materials using such improved marking materials and compounds.
Discussion of Prior Art
Industry has long sought a simple method and marking material formulations to surface mark on metal, glass, ceramic, porcelain, natural and engineered stone, as well as plastics, polymer composites and other organic materials with five attributes. These attributes include color, high-resolution, high contrast, long term durability and speed of application.
Most well known efforts to date have only produced two, three or four of these attributes. For example, kiln firing using glass frit or metal oxide materials at kiln temperatures ranging from 100° C. to more than 1000° C. results in high-resolution, high-contrast, permanent color marks and, decorations on metal, glass, ceramic and porcelain objects. These well known processes require heating the entire substrate object along with the glass frit and/or metal oxide materials in a kiln and require different formulations of the glass frit and/or metal oxide materials depending on the substrate object to be marked or decorated. One problem with these processes is that the time factor and energy consumption are not commercially efficient enough to make the marking or decoration process economically feasible in smaller quantities. Time requirements ranging from several minutes to several hours are common. Furthermore, these processes, requiring a kiln, do not lend themselves to portability.
Another known method is shot-peening or engraving on metal. This method cannot be used on glass, ceramic, porcelain or other brittle materials because of potential surface damage and/or breakage. Where used, the method produces a relatively low-resolution, fast and permanent mark; however, color and high-contrast marking cannot be achieved.
Other known marking methods are direct and transfer printing processes. The transfer method uses a laser or electrostatically transferable toner onto an intermediate carrier in order to enhance the application of heat, or the conversion of laser energy into heat, in order to fuse the toner to the substrate surface. This method produces high-resolution and high-contrast marks or decorations with color, if desired, and is relatively fast, but lacks real long term durability. Conventional laser printers for paper are representative of such processes.
Another known direct printing process involves the use of aerosol jet deposition apparatus such as inkjet printers. In many cases environmentally hazardous solvents are mixed with combinations of organic and/or inorganic components, in order to improve deposition efficiency, performance, adhesion, resolution, appearance and durability. These organic resin or polymer binder systems usually comprise a monomer, oligomer, photopolymerization initiator and various additives (stabilizers, fillers, pigments, etc.) and are used with an ultraviolet lamp curing step which is relatively time consuming; however, even with the use of solvents and ultraviolet curing there remains a lack of long term durability to abrasion, outdoor weather and sunlight conditions.
Another transfer printing method, known as dye-sublimation, employs a printing process that uses heat to transfer dyes onto the surfaces of materials such as plastic, certain papers, or fabric coated with polymeric materials such as polyesters. This process, which takes several minutes, can also be used to mark or decorate the surface of various polymer coated metal, glass, ceramic and porcelain objects. A diffusion of the dye into the polymer material or coated substrate surface is accomplished by a heated, pressurized air step transferring the desired image from a printed transfer label. The resulting mark or decoration is only as durable as the polymer material or coating, but lacks long term ultraviolet stability.
Another related group of marking or decorating methods is based on the use of laser energy combined with different mixtures comprising glass frit, pyrophilic materials, mineral clays, base metals, metal oxides or combinations thereof in order to bond a marking or decoration onto the surface of various metal, glass, ceramic, porcelain, plastic, polymer composite, natural or engineered stone objects. Descriptions of the ingredients and components for these mixtures and methods for laser marking or bonding technology can be found in U.S. Pat. No. 4,769,310 to Gugger et al., U.S. Pat. No. 5,030,551 to Herren et al. and European Patent No. 1,040,017 B1 to Hory et al. Applicant Paul W. Harrison's U.S. Pat. Nos. 6,075,223 and 6,313,436 and European Patent No. 1,040,017 B1, all of which are incorporated herein by reference, disclose flexible methods for marking metals, plastics, ceramic materials, glazes, glass ceramics and glasses without damaging the surfaces thereof and without specific requirements being made of the substrates, these methods involving the use of glass frit based or mixed organic materials or mixed metal oxides in layers for laser marking.
Other relevant patents include that of Nohr et al., U.S. Pat. No. 7,371,456, which disclose nanoparticle-based recording media, inks and ink compositions, methods of making such materials and methods for making nanoparticles plus related technologies. U.S. Pat. No. 8,916,796 to Ramanujan et al. discloses methods and apparatus for depositing and curing nanoparticle-based inks. Thaker's U.S. Pat. No. 8,765,855 discloses ink formulations comprising a binder and at least one marking component, which comprises at least one metal oxide or oxyanion and at least one oxidizing/reducing agent, and absorbs laser irradiation between wavelengths of 780-10,600 nm, thereby causing the formulation to change color. The compounds used can be in particulate form with average particle sizes of 10 nm to 10 micrometers.
U.S. Published Application No. U.S. 2014/0370247 A1 of Detric et al., assigned to Ferro Corporation, discloses laser marking compositions and related methods, in which the compositions can include a molybdenum metal complex, a tungsten metal complex, or combinations thereof. Marks formed on a substrate using the compositions and methods are stated to exhibit increased contrast and improved substrate bonding. The particulate materials used in the compositions can have various sizes, in one embodiment in the range of about 0.1 to 55 microns.
A need remains for marks that exhibit increased contrast and color, if desired, such that the decorations or marks are more readily visible. In addition, for marks subject to surface abrasion, chemical reactions or exposure to environmental elements it would also be beneficial to improve the chemical bonding between the marking composition and the underlying substrate material to prevent or reduce the potential for abrasion or removal. Accordingly, in view of these and other concerns, a need exists for improved marking compositions and methods for using such materials and compositions.